Databases continue to grow. Query languages (e.g., structured query language (SQL)) facilitate producing arbitrarily complex queries that may take inordinate and/or unknowable amounts of time to complete in these growing databases. Conventional strategies to limit the impact of such queries involve a user specifying how to limit a query (e.g., return the “first-few rows”, return “a sample of rows”). However, these strategies require increased sophistication from users and may still produce queries having unknown or unpredictable query processing times.